This invention relates to nuclear reactors and has particular relationship to thermal insulating shielding of such reactors. A nuclear reactor includes a vessel, which in the case of a pressurized water reactor, is a pressure-tight pressure vessel. The vessel includes a generally circular cylindrical body and a dome-shaped head. To conserve the thermal energy generated in the reactor it is desirable that the vessel be thermally shielded. In accordance with the teachings of the prior art, thermal insulating panels are bolted or buckled to the head of the reactor. The panels must be bolted or buckled to the head when the insulation is installed and unbolted or unbuckled from the head when the insulation is removed to afford access for removal of the head. The bolting and unbolting or the buckling and unbuckling are performed manually. In addition, the panels are typically provided with lifting eyes and it is necessary that when removing or installing the panels that the hook of the lift rig be attached to, or removed from, the eyes manually. When panels are being installed on the head or being prepared for removal from the head, personnel will be exposed to radiation. The installation or removal of the panels from the head is also time consuming which not only involves substantial labor cost but also exacerbates the exposure to radiation of the personnel involved. Since personnel can be exposed to radiation during only a limited time interval, the number of persons who must take part in a thermal panel installation or removal opertion is high and the resulting labor cost is high. An additional cost factor results from the requirement that personnel once exposed to radiation must avoid later exposure for several months.
It is an object of this invention to overcome the above-described drawbacks and disadvantages of the prior art and to provide a nuclear reactor having thermal insulation for the head which shall be readily installed or removed in a relatively short time by remote operation avoiding exposure of the installing or removing personnel to radiation.